This invention relates to an improved shock resistant shoe sole which is particularly appropriate for use in running shoes, sneakers and other athletic footwear.
During intense athletic activities such as those which involve sprinting, jogging and other forms of running tremendous impact forces are experienced by the foot as it bears the entire burden of the athlete's weight each time it encounters the ground. In the sport of long distance running, in particular, such impact shock upon the foot may over a prolonged period, repeated a number of times, such stress due to a significant number of injuries to the bones, muscles, joints, ligaments and tendons of the foot and leg have become associated with athletic activity. Recently, because of increased interest in physical fitness, and running in particular, the problem of foot and leg injuries has become acute and widespread. Remedies have focused upon more effective warm-up (e.g. calisthenics) techniques and improved equipment (e.g. running and other athletic shoe) design. Stress injuries to feet and legs persist, however.
The midsole presently employed by the typical athletic shoe does not exhibit both optimal shock resistance and stability control. As the midsole is made of a softer material, (e.g. foam), its shock absorbent qualities are enhanced but stability and control are lost. This occurs because a certain proportion of the impact shock is transmitted up the bone structure to the ankle, causing it to wobble. Harder materials, (e.g. rubber), are more stable (less shock transmitted to the ankle), but result in more of the impact shock being absorbed directly by the foot.